CN112166330B - Battery management device, battery management method and battery pack - Google Patents

Abstract

Provided are a battery management device, a battery management method and a battery pack. The battery management device generates a first data set including a first current value, a first voltage value and a first temperature value indicative of a current, a voltage and a temperature of the battery. The battery management device generates a second data set from the first data set using an error generator. The battery management device determines a first candidate value, a second candidate value and a third candidate value for a state of charge (SOC) based on the first current value, the first data set and the second data set, respectively. The control unit updates the correction value if the second difference between the first candidate value and the third candidate value is smaller than the first difference between the first candidate value and the second candidate value.

Description

Battery management device, battery management method and battery pack

technical field

The present disclosure relates to battery state of charge (SOC) estimation.

This application claims priority from Korean Patent Application No. 10-2019-0008921 filed in Korea on January 23, 2019, the disclosure of which is incorporated herein by reference.

Background technique

Recently, the demand for portable electronic products such as notebook computers, video cameras, and mobile phones has increased dramatically, and with the widespread development of electric vehicles, energy storage batteries, robots, and satellites, much research is being done on batteries that can be repeatedly recharged .

At present, commercially available batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium batteries, etc., and among them, lithium batteries have little or no memory effect, and therefore they can be recharged at any time when it is convenient, and the self-discharge rate is very high. Compared with nickel-based batteries, lithium batteries have attracted more and more attention due to the advantages of low energy consumption and high energy density.

One of the important parameters needed to control battery charging/discharging is the state of charge (SOC). The SOC is a parameter indicating a relative ratio of a remaining capacity to a maximum capacity indicating electric energy stored in a battery when the battery is fully charged, and may be expressed as 0~1 or 0%~100%. For example, when the maximum capacity of the battery is 1000 Ah (ampere-hours), and the remaining capacity of the battery is 750 Ah, the SOC of the battery is 0.75 (or 75%).

Ampere counts and equivalent circuit models are commonly used to estimate the SOC of a battery. According to the amperage count, the SOC of the battery is estimated based on an accumulated current value corresponding to the current flowing through the battery accumulated over time. However, there may be discrepancy between the SOC estimated by ampere counting and the actual SOC due to measurement error of the current sensor and/or external noise. Design an equivalent circuit model to simulate the electrochemical properties of the battery. However, batteries have nonlinear characteristics according to operating states, and it is difficult to design an equivalent circuit model for perfectly simulating the nonlinear characteristics of batteries.

To overcome the above-mentioned shortcomings of each of the ampere counting and equivalent circuit models, battery SOC estimation using an extended Kalman filter has been proposed. The extended Kalman filter using the amperometric and equivalent circuit models in combination achieves a more accurate SOC estimate than when the amperometric or equivalent circuit models are used alone.

In order to estimate the SOC of a battery using the Extended Kalman Filter, it is necessary to determine the time constants of the resistor-capacitor (RC) pairs included in the equivalent circuit model and set Associated two process noises.

However, since the time constant depends only on at least one of the SOC and temperature of the battery and assigns a fixed value to each process noise, it is difficult to properly adjust the ampere count and the battery in the equivalent circuit model for the operating state of the battery and the environment in which the battery is used. the reliability of each.

Contents of the invention

technical problem

The present disclosure is designed to solve the above-mentioned problems, and therefore, the present disclosure aims to provide a battery management device, a battery management method, and a battery pack in which a plurality of candidate values for a state of charge (SOC) of a battery are determined in each cycle, And the SOC of the battery is determined based on the relationship among the plurality of candidate values.

The present disclosure further aims to provide a battery management device, a battery management method, and a battery pack in which the reliability of each of the amperage count in the extended Kalman filter and the equivalent circuit model is adjusted based on the relationship among a plurality of candidate values. sex.

These and other objects and advantages of the present disclosure can be understood through the following description, and will become apparent according to the embodiments of the present disclosure. Furthermore, it will be readily understood that the objects and advantages of the present disclosure can be achieved by the means set forth in the appended claims and combinations thereof.

technical solution

A battery management device according to an aspect of the present disclosure includes: a sensing unit configured to detect a current, a voltage, and a temperature of a battery; and a control unit. The control unit is configured to generate a first data set comprising a first current value indicative of the detected current, a first voltage value indicative of the detected voltage, and a first temperature value indicative of the detected temperature. The control unit is configured to generate a second data set from the first data set using the error generator, the second data set comprising a second current value, a second voltage value and a second temperature value. The control unit is configured to determine a first time constant of an equivalent circuit model of the extended Kalman filter based on the first temperature value and a state of charge (SOC) in a previous cycle. The control unit is configured to determine a second time constant of the equivalent circuit model based on the second temperature value and the SOC in a previous cycle. The control unit is configured to determine a first candidate value for the SOC of the battery based on the first current value using the amperage count. The control unit is configured to determine a second candidate value for the SOC based on the first data set, the first time constant and the correction value using an extended Kalman filter. The control unit is configured to determine a third candidate value for the SOC based on the second data set, the second time constant and the correction value using an extended Kalman filter. The control unit is configured to determine a first difference between the first candidate value and the second candidate value. The control unit is configured to determine a second difference between the first candidate value and the third candidate value. The control unit is configured to update the correction value when the second difference is smaller than the first difference. The updated correction value is greater than a predetermined initial value.

In at least one of the first pair of the first current value and the second current value, the second pair of the first voltage value and the second voltage value, and the third pair of the first temperature value and the second temperature value The two values included in each are different from each other.

A difference between the updated correction value and the initial value may be proportional to the first difference value.

A difference between the updated correction value and the initial value may be proportional to a difference between the first difference value and the second difference value.

The control unit may be configured to update the correction value using the following equation:

D ₁ may represent a first difference, D ₂ may represent a second difference, M ₁ may represent a first weight, M ₂ may represent a second weight, and E _correct may represent an updated correction value.

The control unit may be configured to update the correction value to be equal to the initial value when the second difference is equal to or greater than the first difference.

The control unit may be configured to determine the first candidate value as the SOC when the first difference is greater than a threshold.

The control unit may be configured to determine the second candidate value as the SOC when the first difference value is equal to or smaller than the threshold value.

The control unit may be configured to selectively output a switching signal for controlling a switch installed on a current path of the battery. When the second difference is smaller than the first difference, the control unit is configured to adjust the duty cycle of the switching signal to be lower than the reference duty cycle.

A battery pack according to another aspect of the present disclosure includes a battery management device.

A battery management method according to yet another aspect of the present disclosure, including: detecting the current, voltage and temperature of the battery; generating a first data set including a first current value indicating the detected current, a first current value indicating the detected voltage a voltage value and a first temperature value indicative of the detected temperature, a second data set is generated from the first data set using an error generator, the second data set includes a second current value, a second voltage value, and a second temperature value, based on The first time constant of the equivalent circuit model of the extended Kalman filter is determined based on the first temperature value and the SOC in the previous cycle, and the second time constant of the equivalent circuit model is determined based on the second temperature value and the SOC in the previous cycle. time constant, using ampere counting to determine a first candidate value for the battery's SOC based on a first current value, using Extended Kalman

The filter determines a second candidate value for the SOC based on the first data set, the first time constant and the correction value, and an extended Kalman filter is used to determine the second candidate value for the SOC based on the second data set, the second time constant and the correction value the third candidate value of , determine the first difference between the first candidate value and the second candidate value, determine the second difference between the first candidate value and the third candidate value, and when the second difference is less than the first Update the correction value when there is a difference. The updated correction value is greater than a predetermined initial value.

A difference between the updated correction value and the initial value may be proportional to the first difference or a difference between the first difference and the second difference.

The battery management method may further include: determining the first candidate value as the SOC when the first difference is greater than a threshold; and determining the second candidate as the SOC when the first difference is equal to or less than the threshold.

Function of the present invention

According to at least one embodiment of the present disclosure, it is possible to more accurately determine a state of charge (SOC) of a battery based on a relationship between a plurality of candidate values for the SOC of the battery determined in each cycle.

Furthermore, according to at least one of the embodiments of the present disclosure, it is possible to adjust the reliability of each of the ampere count in the extended Kalman filter and the equivalent circuit model based on the relationship among the plurality of candidate values.

Effects of the present disclosure are not limited to the effects mentioned above, and these and other effects will be clearly understood from the appended claims by those skilled in the art.

Description of drawings

FIG. 1 is an example diagram of a configuration of a battery pack according to the present disclosure.

FIG. 2 is an example diagram of a circuit configuration of an equivalent circuit model of a battery.

FIG. 3 is an example graph of an open circuit voltage (OCV)-state of charge (SOC) curve of a battery.

4 and 5 are exemplary flowcharts of a battery management method according to the first embodiment of the present disclosure.

6 and 7 are exemplary flowcharts of a battery management method according to a second embodiment of the present disclosure.

Detailed ways

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in the specification and appended claims should not be construed as limited to their ordinary and dictionary meanings, but rather under the principle of allowing the inventor to properly define the terms for best interpretation Based on the meaning and concept corresponding to the technical aspect of the present invention, it is interpreted.

Therefore, the embodiments described herein and the illustrations shown in the drawings are only the most preferred embodiments of the present disclosure, and are not intended to fully describe the technical aspects of the present disclosure, so it should be understood that the Various other equivalents and modifications are made.

Terms including ordinal numbers, such as 'first', 'second', etc., are used to distinguish one element from another among various elements, but the elements are not intended to be limited by these terms.

Unless the context clearly dictates otherwise, it will be understood that when used in this specification the term "comprising" specifies the presence of stated elements but does not exclude the presence or addition of one or more other elements. In addition, the term <control unit> as used herein refers to a processing unit having at least one function or operation, and this can be realized by hardware or software or a combination of hardware and software.

Also, throughout the specification, it will be further understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may be present.

1 is an exemplary diagram of a configuration of a battery pack according to an embodiment of the present disclosure, FIG. 2 is an exemplary diagram of a circuit configuration of an equivalent circuit model of a battery, and FIG. 3 is an open circuit voltage (OCV)-state of charge (SOC) of a battery. ) example plot of the curve.

Referring to FIG. 1 , a battery pack 10 is configured to supply power required by electric equipment such as an electric vehicle 1 , and includes a battery 20 , a switch 30 and a battery management device 100 .

The battery 20 includes at least one battery cell. Each battery cell may be, for example, a lithium-ion cell. Of course, the type of battery cell is not limited to lithium-ion cells, and may include, but is not limited to, any type that can be repeatedly recharged. Each battery cell included in the battery 20 is electrically connected to other battery cells in series or in parallel.

The switch 30 is installed on a current path for charging and discharging the battery 20 . A control terminal of the switch 30 is provided to be electrically connected to the control unit 120 . The switch 30 is controlled to be turned on and off according to a duty ratio of the switching signal SS output by the control unit 120 in response to the switching signal SS being applied to the control terminal. When the switch signal SS is at a high level, the switch 30 can be turned on, and when the switch signal SS is at a low level, the switch 30 can be turned off.

The battery management device 100 is configured to be electrically connected to the battery 20 to periodically determine the SOC of the battery 20 . The battery management device 100 includes a sensing unit 110 , a control unit 120 , a storage unit 130 and a communication unit 140 .

The sensing unit 110 is configured to detect voltage, current and temperature of the battery 20 . The sensing unit 110 includes a current sensor 111 , a voltage sensor 112 and a temperature sensor 113 .

The current sensor 111 is provided to be electrically connected to the charging/discharging path of the battery 20 . The current sensor 111 is configured to detect a current flowing through the battery 20 and output a signal SI indicative of the detected current to the control unit 120 .

A voltage sensor 112 is provided to be electrically connected to the positive and negative terminals of the battery 20 . The voltage sensor 112 is configured to detect a voltage across the positive and negative terminals of the battery 20 and output a signal SV indicative of the detected voltage to the control unit 120 .

The temperature sensor 113 is configured to detect the temperature of an area within a predetermined distance from the battery 20 and output a signal ST indicative of the detected temperature to the control unit 120 .

The control unit 120 is operatively coupled to the sensing unit 110 , the storage unit 130 , the communication unit 140 and the switch 30 . The control unit 120 may use application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), microprocessors, and At least one of the electrical units for performing other functions is implemented in hardware.

The control unit 120 is configured to periodically receive the signal SI, the signal SV and the signal ST output by the sensing unit 110 . The control unit 120 is configured to use an analog-to-digital converter (ADC) included in the control unit 120 to determine a first current value, a first voltage value, and a first temperature value from the signal SI, the signal SV, and the signal ST, respectively, and will include A first data set of the first current value, the first voltage value and the first temperature value is stored in the storage unit 130 .

The storage unit 130 is operatively coupled to the control unit 120 . The storage unit 130 may store programs and data necessary to perform steps described below. The storage unit 130 may include, for example, a flash memory type, a hard disk type, a solid state disk (SSD) type, a silicon disk drive (SDD) type, a multimedia card mini type, random access memory (RAM), static random access memory (SRAM), At least one type of storage medium selected from Read Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), and Programmable Read Only Memory (PROM).

The communication unit 140 may be coupled to communicate with an external device 2 such as an electronic control unit (ECU) of the electric vehicle 1 . The communication unit 140 may receive a command message from the external device 2 and provide the received command message to the control unit 120 . The command message may be a message requesting activation of a specific function of the battery management device 100 (eg, SOC estimation, control of on/off of the switch 30 ). The communication unit 140 may transmit a notification message from the control unit 120 to the external device 2 . The notification message may be a message for notifying the external device 2 of the result of the function performed by the control unit 120 (for example, estimated SOC). For example, the communication unit 140 may communicate with the external device 2 via a wired network such as a local area network (LAN), a controller area network (CAN), and a daisy chain, and/or a short-range wireless network such as Bluetooth, Zigbee, and WiFi.

The control unit 120 is configured to determine a state of health (SOH) or maximum capacity of the battery 20 . The maximum capacity indicates the maximum amount of charge that can currently be stored in the battery 20, and may be referred to as "full charge capacity". That is, the maximum capacity is equal to the cumulative value of the current flowing during the discharge of the battery 20 with the SOC of 1 (=100%) until the SOC of 0 (=0%). In an example, the control unit 120 may calculate the internal resistance of the battery 20 and determine the SOH or maximum capacity of the battery 20 based on a difference between the calculated internal resistance and a reference resistance. In another example, the control unit 120 may use the following Equation 1 based on the SOC at each different time point when the battery 20 is charged and discharged and the accumulated current value during the time period between the two time points. The SOH or maximum capacity of the battery 20 is determined. Assume that the earlier time point of the two time points is t ₁ , and the later time point is t ₂ .

<equation 1>

In Equation 1, Q _ref represents the reference capacity, SOC ₁ represents the estimated SOC at time point _t1 , SOC ₂ represents the estimated SOC at time point _t2 , ΔSOC represents the difference between SOC ₁ and SOC ₂ , _it represents the current value indicating the current detected at the time point t between the time point _t1 and the time point _t2 , ΔC represents the accumulated current value during the period from the time point _t1 to the time point _t2 , and Q _est represents The estimate of the maximum capacity at the time point _t2 , and SOH _new represents the estimate of the SOH at the time point _t2 . Q _ref is a preset value indicating the maximum capacity when the SOH of the battery 20 is 1, and may be pre-stored in the storage unit 130 .

Regarding Equation 1, when ΔSOC is too small, Q _est may be greatly different from the actual value. Therefore, the control unit 120 may be configured to determine the SOH or the maximum capacity of the battery 20 using Equation 1 only when ΔSOC is equal to or greater than a predetermined value (eg, 0.5).

Hereinafter, the operation performed by the control unit 120 for estimating the SOC of the battery 20 will be described in more detail.

The control unit 120 determines the first candidate value based on the first current value using the amperage count. The first candidate value indicates an estimate of the SOC of battery 20 for the current cycle. Equation 2 below may be used to determine the first candidate value.

<equation 2>

The following is a description of the symbols used in Equation 2. Δt represents the time length of each cycle. k is a time index that increases by 1 every time Δt elapses, and indicates the number of cycles from the time point at which a predetermined event occurs to the current time point. This event may be, for example, a start event of charging and discharging of the battery 20 whose voltage is stabilized. The voltage-stabilized battery 20 may be the battery 20 under no-load conditions in which current does not flow through the battery 20 and the voltage of the battery 20 is uniformly maintained. In this case, SOC _e [0] is determined from the OCV-SOC curve defining the correspondence between the OCV and SOC of the battery 20 using the OCV of the battery 20 at the time point when the event occurs as an index. The OCV-SOC curve is stored in the storage unit 130 .

In Equation 2, i[k+1] represents the current detected in the current cycle, and SOC _e [k] represents the SOC determined by ampere counting or the extended Kalman filter in the previous cycle. SOC[k+1] is the first candidate value, and indicates the SOC determined using Equation 2. In Equation 2, i[k+1] can be replaced by i[k].

The control unit 120 further uses an extended Kalman filter to determine the second candidate value and the third candidate value. The second candidate value is indicative of an estimate of the SOC of battery 20 for the current cycle. Before describing the second and third candidate values, the extended Kalman filter will be described.

The extended Kalman filter is an algorithm for periodically updating the SOC of the battery 20 by additionally using the equivalent circuit model 200 of the battery 20 together with the amperage count expressed by Equation 2.

Referring to FIG. 2 , equivalent circuit model 200 includes OCV source 210 , ohmic resistor R ₁ and resistor-capacitor (RC) pair 220 .

OCV source 210 simulates OCV, which is the voltage between the positive and negative electrodes of battery 20 that is electrochemically stable over time. The OCV output by the OCV source 210 has a nonlinear function relationship with the SOC of the battery 20 . That is, OCV=f ₁ (SOC), SOC=f ₂ (OCV), and f ₁ and f ₂ are inverse functions of each other. For example, referring to FIG. 3 , 3.3V=f ₁ (0.5) and 0.7=f ₂ (3.47V).

The OCV output by the OCV source 210 may be preset by SOC and temperature through experiments.

The ohmic resistor R ₁ is associated with the IR voltage drop V ₁ of the battery 20 . IR drop refers to the instantaneous change in voltage across the battery 20 as the battery 20 switches from an unloaded state to a charge/discharge state or vice versa. In an example, the measured voltage of the battery 20 is higher than the OCV at the point in time when the battery 20 starts charging under the no-load condition. In another example, the measured voltage of the battery 20 is lower than the OCV at the point in time when the battery 20 starts to discharge under the no-load condition. The resistance value of the ohmic resistor R ₁ can also be preset experimentally through SOC and temperature.

The RC pair 220 outputs an overpotential (also referred to as “polarization voltage”) V ₂ induced by the electric double layer of the battery 20 or the like, and includes a resistor R ₂ and a capacitor C ₂ connected in parallel. The overpotential _V2 may be referred to as "polarization voltage". The time constant of the RC pair 220 is the product of the resistance value of the resistor _R2 and the capacitance of the capacitor _C2 , and can be preset by SOC and temperature through experiments.

V _ecm is the output voltage of the equivalent circuit model 200 and is equal to the sum of OCV from the OCV source 210 , the IR drop V ₁ across the ohmic resistor R ₁ , and the overpotential V ₂ across the RC pair 220 .

The current sensitivity of the equivalent circuit model 200 to the current flowing through the battery 20 is higher as the time constant of the RC pair 220 is smaller. Conversely, as the time constant of the RC pair 220 is larger, the current sensitivity of the equivalent circuit model 200 to the current flowing through the battery 20 is lower. Under the same conditions, as the current sensitivity of the equivalent circuit model 200 is higher, V _ecm changes faster. On the contrary, as the current sensitivity of the equivalent circuit model 200 is lower, V _ecm changes more slowly.

In the equivalent circuit model 200, the overpotential in the current cycle can be defined as Equation 3 below.

<equation 3>

In Equation 3, _R2 [k+1] represents the resistance value of resistor _R2 in the current cycle, τ[k+1] represents the time constant of the RC pair 220 in the current cycle, and _V2 [k] represents The overpotential in the previous cycle, and V ₂ [k+1] represents the overpotential in the current cycle. In Equation 3, i[k] may be substituted for i[k+1]. The overpotential V ₂ [0] at the time point when the event occurs may be 0V (volt).

Equation 4 below is a first state equation associated with the time update process of the extended Kalman filter, and is derived from a combination of Equation 2 and Equation 3.

<equation 4>

In Equation 4 and the following Equations 5 to 8, the superscript symbol ^ indicates a value estimated by time update. In addition, the superscript symbol ^- indicates the value before correction by the measurement update described below.

Equation 5 below is a second state equation associated with the time update process of the extended Kalman filter.

<equation 5>

In Equation 5, P _k represents the error covariance matrix corrected in the previous cycle, Q _k represents the process noise covariance matrix in the previous cycle, T represents the transpose operator, and P ⁻ _k+1 represents The error covariance matrix for the current period. When k=0, P ₀ may be equal to [1 0; 0 1]. W _lk is the first process noise set in the previous cycle and is associated with the reliability of the amperage count. That is, W1 _k is a positive number indicating the inaccuracy of the integrated current value calculated using the ampere count. W2 _k is the second process noise set in the previous cycle and is associated with the reliability of the equivalent circuit model 200 . That is, W2 _k is a positive number indicating the inaccuracy of the parameters associated with the equivalent circuit model 200 . Therefore, the control unit 120 may increase the first process noise as the inaccuracy of the ampere count increases. As the inaccuracy of the equivalent circuit model 200 increases, the control unit 120 may increase the second process noise.

When the time update process using Equation 4 and Equation 5 is completed, the control unit 120 performs the measurement update process.

Equation 6 below is a first observation equation associated with the measurement update process of the extended Kalman filter.

<equation 6>

In Equation 6, K _k+1 represents the Kalman gain in the current cycle. In addition, R is the measurement noise covariance matrix and has preset components. H _k+1 is a system matrix, and is used to reflect changes in the OCV of the battery 20 from the OCV-SOC curve when estimating the SOC of the battery 20 . n is a preset positive integer (for example, 1).

Equation 7 below is a second observation equation associated with the measurement update process of the extended Kalman filter.

<equation 7>

In Equation 7, z _k+1 represents the voltage of the battery 20 measured in the current cycle, and V _ecm [k+1] represents the output voltage of the equivalent circuit model 200 in the current cycle. f ₁ (SOC[k+1]) represents the OCV in the current cycle (see description of FIG. 2 ). V ₁ [k+1] represents the voltage across the ohmic resistor R ₁ in the current cycle, and may be equal to the product of one of i[k+1] and i[k] and R ₁ [k+1]. R ₁ [k+1] is the resistance value of the ohmic resistor R ₁ in the current cycle. The control unit 120 may determine R ₁ [k+1] based on the first temperature value and the SOC determined in the previous cycle. For this, a first look-up table defining a correspondence relationship between the SOC, the temperature value, and the resistance value of the ohmic resistor R ₁ is recorded in the storage unit 130 . The control unit 120 may obtain the resistance value mapped to the specific temperature value (eg, the first temperature value) and the specific SOC from the first lookup table using the specific temperature value and the specific SOC as indexes. Each of SOC[k+1] and V ₂ [k+1] obtained from Equation 4 is corrected by Equation 7.

Equation 8 below is a third observation equation associated with the measurement update process of the extended Kalman filter.

<equation 8>

In Equation 8, E represents an identity matrix. P ⁻ _k+1 obtained from Equation 5 is corrected to P _k+1 by Equation 8.

The control unit 120 periodically updates the SOC of the battery 20 in the current cycle by performing each calculation step of Equations 4 to 8 at least once each time the time index k increases by 1.

Hereinafter, the operation of determining the second candidate value and the third candidate value will be described with reference to the above description of the extended Kalman filter.

The control unit 120 determines a second candidate value based on the first data set. As previously stated, the first data set includes a first current value, a first voltage value, and a first temperature value. The control unit 120 determines R ₂ [k+1] and τ[k+1] of Equation 4 based on the first temperature value and the SOC determined in the previous cycle.

To this end, the storage unit 130 may record a second lookup table that defines a correspondence relationship between the SOC, the temperature value, and the resistance value of the resistor _R2 . The control unit 120 may obtain the resistance value mapped to the first temperature value and the SOC determined in the previous cycle from the second lookup table using the first temperature value and the SOC determined in the previous cycle as an index, as the equation R ₂ [k+1] of 4. In addition, the storage unit 130 may record a third lookup table that defines the correspondence between the SOC, the temperature value, and the time constant. The control unit 120 may use the first temperature value and the SOC determined in the previous cycle as an index to obtain a time constant mapped to the first temperature value and the SOC determined in the previous cycle from the third lookup table as the first time constant. The control unit 120 may set, as τ[k+1] of Equation 4, a value obtained by adding the first time constant to the correction value determined in the previous period. When k=0, a predetermined initial value (for example, 0) may be used as the correction value. The determination of the correction value will be described below.

The control unit 120 sets i[k+1] (or i[k]) of Equation 4 equal to the first current value, and sets z _k+1 of Equation 7 equal to the first voltage value. Accordingly, the control unit 120 may determine SOC[k+1] corrected by Equation 7 as the second candidate value.

The control unit 120 converts the first data set into a second data set, and determines a third candidate value based on the second data set. In detail, the control unit 120 may generate the second data set from the first data set using an error generator. In consideration of detection accuracy of the sensing unit 110 or external noise, the control unit 120 operates the error generator to forcibly vary at least one of the first current value, the first voltage value, and the first temperature value included in the first data set . The second data set includes a second current value, a second voltage value, and a second temperature value. That is, the error generator may be a predetermined function coded to selectively change from a first current value to a second current value, from a first voltage value to a second voltage value, and from a first temperature value At least one of the changes to the second temperature value. For example, the second current value=(first current value×X ₁ )+X ₂ , the second voltage value=(first voltage value×X ₃ )+X ₄ , and the second temperature value=(first temperature value× X ₅ )+X ₆ . X ₁ to X ₆ may be constants preset to be the same as or different from each other.

The two values included in each of at least one of a pair of first and second current values, a pair of first and second voltage values, and a pair of first and second temperature values are mutually mutually different. In an example, the first current value and the second current value may be equal to each other, and the first voltage value and the second voltage value may be different from each other, and the first temperature value and the second temperature value may also be different from each other. In another example, the first current value and the second current value may be different from each other, the first voltage value and the second voltage value may be different from each other, and the first temperature value and the second temperature value may also be different from each other.

When generating the second data set, the control unit 120 may determine R ₂ [k+1] and τ[k+1] of Equation 4 based on the second temperature value and the SOC determined in the previous cycle.

In detail, the control unit 120 may obtain the resistance value mapped to the second temperature value and the SOC determined in the previous cycle as R ₂ [k+1] of Equation 4 from the second lookup table. The control unit 120 may obtain the second time constant mapped to the second temperature value and the SOC determined in the previous cycle from the third look-up table. The control unit 120 may set a value obtained by adding the second time constant to the correction value as τ[k+1] of Equation 4.

The control unit 120 sets i[k+1] (or i[k]) of Equation 4 equal to the second current value instead of the first current value. In addition, the control unit 120 sets z _k+1 of Equation 7 to be equal to the second voltage value instead of the first voltage value. Accordingly, the control unit 120 may determine SOC[k+1] corrected by Equation 7 as the third candidate value.

When the determination of the first candidate value, the second candidate value and the third candidate value for the SOC of the battery 20 is completed in the current cycle, the control unit 120 is configured to select one of the first candidate value and the second candidate value Either one, and the selected candidate value is determined as the SOC in the current cycle by the process described below.

The control unit 120 determines a first difference value which is the absolute value of the difference between the first candidate value and the second candidate value. In an example, when the first candidate value is 0.51 and the second candidate value is 0.52, the first difference is 0.01. In another example, when the first candidate value is 0.77 and the second candidate value is 0.75, the first difference is 0.02.

The control unit 120 determines a second difference value which is the absolute value of the difference between the first candidate value and the third candidate value. In an example, when the first candidate value is 0.61 and the third candidate value is 0.64, the second difference is 0.03. In another example, when the first candidate value is 0.38 and the second candidate value is 0.36, the second difference is 0.02.

The control unit 120 may compare the first difference with a predetermined threshold. The threshold is stored in the storage unit 130, and may be, for example, 0.03.

When the first difference is greater than the threshold, the control unit 120 may determine the first candidate value as the SOC of the battery 20 .

When the first difference value is equal to or less than the threshold value, the control unit 120 determines the second candidate value instead of the first candidate value as the SOC of the battery 20 .

The control unit 120 may compare the first difference with the second difference. When the second difference is equal to or greater than the first difference, the control unit 120 may set the ratio of the second process noise to the first process noise to be equal to a predetermined reference ratio (eg, 0.1). For example, the first process noise may be set equal to a predetermined first reference value (eg, 0.1), and the second process noise may be set equal to a predetermined second reference value (eg, 0.01). That is, the reference ratio may be equal to a value obtained by dividing the second reference value by the first reference value.

When the second difference is equal to or greater than the first difference, the control unit 120 may set the correction value equal to the initial value. The control unit 120 may store the correction value set equal to the initial value in the storage unit 130 .

Meanwhile, referring to Equation 2 regarding the amperage count, the first candidate value depends only on the current among the current, voltage, and temperature of the battery 20 . On the other hand, referring to Equations 3 to 8 regarding the extended Kalman filter, the second candidate value may depend on the current of the battery 20 and the voltage and temperature of the battery 20 . When this is considered, it can be seen that as the inaccuracy of the equivalent circuit model 200 is higher, there is a higher probability that the second difference will be smaller than the first difference.

Therefore, when the second difference is smaller than the first difference, the control unit 120 may increase the ratio of the second process noise to the first process noise to be higher than the reference ratio. In an example, the first process noise may be set to a value smaller than the first reference value (eg, 0.07), and the second process noise may be set to be equal to the second reference value. In another example, the first process noise may be set equal to the first reference value, and the second process noise may be set at a value greater than the second reference value (eg, 0.02). In yet another example, the first process noise may be set to a value smaller than the first reference value, and the second process noise may be set to a value larger than the second reference value.

When the second difference is smaller than the first difference, the control unit 120 may determine a ratio of the second process noise to the first process noise in proportion to the first difference. In an example, when the first difference is 0.01, the control unit 120 may determine the ratio of the second process noise to the first process noise as 0.11, and when the first difference is 0.013, the control unit 120 may determine the ratio of the second process noise to the first process noise The ratio of the noise to the first process noise is determined to be 0.112, and when the first difference is 0.008, the control unit 120 may determine the ratio of the second process noise to the first process noise to be 0.103.

Alternatively, when the second difference is smaller than the first difference, the control unit 120 may determine that the second process noise is different from the first process noise in proportion to the absolute value of the difference between the first difference and the second difference. The ratio.

The first process noise and the second process noise set as described above may be allocated to W1 _k and W2 _k of Equation 5, respectively, in the process of estimating the SOC in the next cycle. Therefore, when the extended Kalman filter is executed in the next cycle, the reliability (ie, influence) of the equivalent circuit model 200 temporarily decreases, and the reliability of the ampere count temporarily increases.

When the second difference is smaller than the first difference, the control unit 120 may update the correction value to a value greater than the initial value. The control unit 120 may store the updated correction value in the storage unit 130 .

When the second difference is smaller than the first difference, the control unit 120 may determine an updated correction value such that a difference between the updated correction value and the initial value is proportional to the first difference. For example, when the first difference is 0.01, the updated correction value may be determined to be 5 greater than the initial value, and when the first difference is 0.013, the updated correction value may be determined to be 6 greater than the initial value.

Alternatively, when the second difference is smaller than the first difference, the control unit 120 may determine an updated correction value such that the difference between the updated correction value and the initial value is equal to the difference between the first difference and the second difference. The difference is proportional. For example, when the first difference is 0.01 greater than the second difference, the updated correction value can be determined to be 4 greater than the initial value, and when the first difference is 0.013 greater than the second difference, the updated correction value can be determined to be 0.013 greater than the second difference. The value was determined to be 4.5 larger than the initial value.

Alternatively, when the second difference is smaller than the first difference, the control unit 120 may update the correction value using Equation 9 below.

<equation 9>

In Equation 9, D ₁ represents a first difference value, D ₂ represents a second difference value, M ₁ represents a first weight, M ₂ represents a second weight, and E _correct represents an updated correction value. Each of M ₁ and M ₂ may be a preset positive number, and they may be the same as or different from each other.

The correction value updated as described above may be stored in the storage unit 130, and may correspond to each of the first time constant and the second time constant to be obtained in the next cycle in the process of estimating the SOC for the next cycle. add.

In detail, in the process of determining the second candidate value based on the first data set in the next cycle, the sum of the updated correction value and the first time constant in the next cycle can be assigned to τ[k+1 ]. In addition, in the process of determining the third candidate value based on the second data set in the next cycle, the sum of the updated correction value and the second time constant in the next cycle can be assigned to τ[k+1] of Equation 4 .

As previously described, as the time constant of the RC pair 220 is larger, the current sensitivity of the equivalent circuit model 200 is lower. When the Extended Kalman Filter is executed in the next cycle, τ[k+1] of Equation 4 increases the difference between the updated correction value and the initial value, and thus, the reliability of the equivalent circuit model 200 (i.e. , effect) temporarily decreases, and the reliability of the ampere count increases temporarily.

The control unit 120 can selectively output the switch signal SS to control the switch 30 . When the second difference is smaller than the first difference, the control unit 120 may adjust the duty ratio of the switching signal SS to be lower than a predetermined reference duty ratio (eg, 0.2). When the duty ratio of the switching signal SS is adjusted to be lower than the reference duty ratio, the maximum amount of current that can flow through the battery 20 is reduced, thereby avoiding rapid changes in voltage and temperature of the battery 20 .

4 and 5 are exemplary flowcharts of a battery management method according to the first embodiment of the present disclosure. The methods of FIG. 4 and FIG. 5 may be performed periodically from the point in time when the event occurs. The methods of FIGS. 4 and 5 may end when charging/discharging of the battery 20 ceases.

1 to 5, in step S400, the control unit 120 determines the maximum capacity (or SOH) of the battery 20 (see Equation 1).

In step S405 , the control unit 120 detects the current, voltage and temperature of the battery 20 using the sensing unit 110 . The sensing unit 110 outputs a signal SI indicating a detected current, a signal SV indicating a detected voltage, and a signal ST indicating a detected temperature to the control unit 120 .

In step S410, the control unit 120 receives the signal SI, the signal SV and the signal ST, and generates a first data set, the first data set includes a first current value indicating the current of the battery 20, a first value indicating the voltage of the battery 20 A voltage value and a first temperature value indicating the temperature of the battery 20 .

In step S412, the control unit 120 generates a second data set from the first data set using an error generator. The second data set includes a second current value, a second voltage value, and a second temperature value.

In step S420, the control unit 120 determines a first candidate value for the SOC of the battery 20 based on the first current value using the ampere count (see Equation 2).

In step S430, the control unit 120 determines a second candidate value for the SOC of the battery 20 based on the first data set using an extended Kalman filter (see Equations 3 to 8).

In step S440, the control unit 120 determines a third candidate value for the SOC of the battery 20 based on the second data set using an extended Kalman filter (see Equations 3 to 8). Contrary to FIG. 4 , any two or all of steps S420 , S430 and S440 may be performed simultaneously. The order of steps S420, S430, and S440 may be changed as necessary.

In step S450, the control unit 120 determines a first difference between the first candidate value and the second candidate value.

In step S460, the control unit 120 determines a second difference between the first candidate value and the third candidate value. Contrary to that of FIG. 4, steps S450 and S460 may be performed simultaneously. The order of steps S450 and S460 may be changed as necessary.

In step S500, the control unit 120 determines whether the first difference is greater than a threshold. When the value of step S500 is "Yes", step S510 is executed. When the value of step S500 is "No", step S520 is executed.

In step S510 , the control unit 120 determines the first candidate value as the SOC of the battery 20 .

In step S520 , the control unit 120 determines the second candidate value as the SOC of the battery 20 .

In step S530, the control unit 120 determines whether the second difference is smaller than the first difference. When the value of step S530 is "No", step S540 is executed. When the value of step S530 is "Yes", at least one of steps S550 and S560 is performed.

In step S540, the control unit 120 sets the ratio of the second process noise to the first process noise to be equal to the reference ratio. For example, the first process noise may be set equal to a first reference value, and the second process noise may be set equal to a second reference value. The reference ratio is a value obtained by dividing the second reference value by the first reference value.

In step S550, the control unit 120 increases the ratio of the second process noise to the first process noise to be higher than the reference ratio.

In step S560, the control unit 120 adjusts the duty ratio of the switching signal SS output to the switch 30 to be lower than the reference duty ratio. A difference between the adjusted duty cycle and the reference duty cycle may be proportional to a difference between the first difference value and the second difference value.

6 and 7 are exemplary flowcharts of a battery management method according to a second embodiment of the present disclosure. The methods shown in FIG. 6 and FIG. 7 may be executed periodically from the point in time when the event occurs. The methods of FIGS. 6 and 7 may end when charging/discharging of the battery 20 ceases.

Referring to FIGS. 1 to 3 , 6 and 7 , in step S600 , the control unit 120 determines the maximum capacity (or SOH) of the battery 20 (see Equation 1).

In step S605 , the control unit 120 detects the current, voltage and temperature of the battery 20 using the sensing unit 110 . The sensing unit 110 outputs a signal SI indicating a detected current, a signal SV indicating a detected voltage, and a signal ST indicating a detected temperature to the control unit 120 .

In step S610, the control unit 120 receives the signal SI, the signal SV and the signal ST, and generates a first data set, the first data set includes a first current value indicating the current of the battery 20, a first value indicating the voltage of the battery 20 A voltage value and a first temperature value indicating the temperature of the battery 20 .

In step S612, the control unit 120 generates a second data set from the first data set using an error generator. The second data set includes a second current value, a second voltage value, and a second temperature value.

In step S614, the control unit 120 determines a first time constant of the equivalent circuit model 200 based on the first temperature value and the SOC in the previous cycle.

In step S616, the control unit 120 determines a second time constant of the equivalent circuit model 200 based on the second temperature value and the SOC in the previous cycle. As described above, each of the first time constant in step S614 and the second time constant in step S616 may be obtained from the third lookup table. Contrary to FIG. 6, steps S614 and S616 may be performed simultaneously, or step S616 may be performed before step S614.

In step S620, the control unit 120 determines a first candidate value for the SOC of the battery 20 based on the first current value using the ampere count (see Equation 2).

In step S630, the control unit 120 uses an extended Kalman filter for determining a second candidate value of the SOC of the battery 20 based on the first data set, the first time constant and the correction value (see Equations 3 to 8).

In step S640, the control unit 120 determines a third candidate value for the SOC of the battery 20 based on the second data set, the second time constant and the correction value using the extended Kalman filter (see Equations 3 to 8). Contrary to FIG. 6, any two or all of steps S620, S630 and S640 may be performed simultaneously. The order of steps S620, S630, and S640 may be changed as necessary.

In step S650, the control unit 120 determines a first difference between the first candidate value and the second candidate value.

In step S660, the control unit 120 determines a second difference between the first candidate value and the third candidate value. Contrary to FIG. 6, steps S650 and S660 may be performed simultaneously, or step S660 may be before step S650.

In step S700, the control unit 120 determines whether the first difference is greater than a threshold. When the value of step S700 is "Yes", step S710 is executed. When the value of step S700 is "No", step S720 is executed.

In step S710 , the control unit 120 determines the first candidate value as the SOC of the battery 20 .

In step S720 , the control unit 120 determines the second candidate value as the SOC of the battery 20 .

In step S730, the control unit 120 determines whether the second difference is smaller than the first difference. When the value of step S730 is "No", step S740 is executed. When the value of step S730 is "Yes", at least one of steps S750 and S760 is performed.

In step S740, the control unit 120 sets the correction value equal to the initial value.

In step S750, the control unit 120 updates the correction value to a value greater than the initial value (see Equation 9). When steps S630 and S640 are performed in the next cycle, the correction value updated in step S750 may be used to determine the second candidate value and the third candidate value.

In step S760, the control unit 120 adjusts the duty ratio of the switching signal SS output to the switch 30 to be lower than the reference duty ratio. A difference between the adjusted duty cycle and the reference duty cycle may be proportional to a difference between the first difference value and the second difference value.

Although the battery management methods of FIGS. 4 and 5 and the battery management methods of FIGS. 6 and 7 are described separately, when specific steps of either of the two battery management methods are performed, another battery management method may be performed together. specific steps of the method. In an example, when step S740 is performed, step S540 may be performed together. In another example, when step S750 is performed, step S550 may be performed together.

The embodiments of the present disclosure described above can be realized not only by devices and methods, but also by a program that executes functions corresponding to the configurations of the embodiments of the present disclosure or a recording medium on which the program is recorded, and the present A person skilled in the art can easily implement such an embodiment from the disclosure of the previously described embodiments.

Although the present disclosure has been described above with respect to a limited number of embodiments and drawings, the present disclosure is not limited thereto, and it will be obvious to those skilled in the art that, in terms of the technical aspects of the present disclosure and the appended claims, etc. Various modifications and changes can be made therein within the scope of validity.

In addition, since those skilled in the art can make many substitutions, modifications, and changes to the present disclosure described above without departing from the technical aspect of the present disclosure, the present disclosure is not limited to the above-mentioned embodiments and drawings and some or all The embodiments can be selectively combined to allow various modifications.

Claims (15)

1. A battery management device, comprising: a sensing unit configured to detect current, voltage and temperature of the battery; and a control unit configured to generate a first data set comprising a first current value indicative of the detected current, a first voltage value indicative of the detected voltage, and a first value indicative of the detected temperature the first temperature value of Wherein, the control unit is configured to: generating a second data set from the first data set using an error generator, the second data set comprising a second current value, a second voltage value, and a second temperature value, determining a first time constant of an equivalent circuit model of an extended Kalman filter based on said first temperature value and a state of charge (SOC) in a previous cycle, determining a second time constant of the equivalent circuit model based on the second temperature value and the SOC in the previous cycle, determining a first candidate value for the SOC of the battery based on the first current value using ampere counting, determining a second candidate value for the SOC based on the first data set, the first time constant and a correction value using the Extended Kalman Filter, determining a third candidate value for the SOC based on the second data set, the second time constant and the correction value using the extended Kalman filter, determining a first difference between said first candidate value and said second candidate value, determining a second difference between said first candidate value and said third candidate value, and updating said correction value when said second difference is less than said first difference, and Wherein, the updated correction value is greater than a predetermined initial value, and Wherein, at least one of the first pair formed by the first current value and the second current value, the second pair formed by the first voltage value and the second voltage value, and the third pair formed by the first temperature value and the second temperature value The two values included in each of are different from each other. 2. The battery management device according to claim 1, wherein a difference between the updated correction value and the initial value is proportional to the first difference value. 3. The battery management device according to claim 1, wherein a difference between the updated correction value and the initial value is proportional to a difference between the first difference value and the second difference value. 4. The battery management device according to claim 1, wherein the control unit is configured to update the correction value using the following equation:

Wherein, D ₁ represents the first difference, D ₂ represents the second difference, M ₁ represents the first weight, M ₂ represents the second weight, and E _correct represents the updated correction value. 5. The battery management device according to claim 1, wherein the control unit is configured to update the correction value to be equal to the first difference when the second difference is equal to or greater than the first difference. the above initial value. 6. The battery management device according to claim 1, wherein the control unit is configured to determine the first candidate value as the SOC when the first difference is greater than a threshold. 7. The battery management device according to claim 6, wherein the control unit is configured to determine the second candidate value as the SOC when the first difference value is equal to or smaller than the threshold value . 8. The battery management device according to claim 1, wherein the control unit is configured to: selectively outputting a switching signal for controlling a switch mounted on a current path of the battery, and When the second difference is smaller than the first difference, the duty cycle of the switching signal is adjusted to be lower than a reference duty cycle. 9. A battery pack comprising the battery management device according to any one of claims 1 to 8. 10. A battery management method, comprising: Detect battery current, voltage and temperature; generating a first data set comprising a first current value indicative of the detected current, a first voltage value indicative of the detected voltage, and a first temperature value indicative of the detected temperature; generating a second data set from the first data set using an error generator, the second data set including a second current value, a second voltage value, and a second temperature value; determining a first time constant of an equivalent circuit model of an extended Kalman filter based on the first temperature value and a state of charge (SOC) in a previous cycle; determining a second time constant of the equivalent circuit model based on the second temperature value and the SOC in the previous cycle; determining a first candidate value for an SOC of the battery based on the first current value using ampere counting; determining a second candidate value for the SOC based on the first data set, the first time constant, and a correction value using the Extended Kalman Filter; determining a third candidate value for the SOC based on the second data set, the second time constant, and the correction value using the extended Kalman filter; determining a first difference between the first candidate value and the second candidate value; determining a second difference between the first candidate value and the third candidate value; and updating said correction value when said second difference is less than said first difference, and wherein the updated correction value is greater than a predetermined initial value, and Wherein, at least one of the first pair formed by the first current value and the second current value, the second pair formed by the first voltage value and the second voltage value, and the third pair formed by the first temperature value and the second temperature value The two values included in each of are different from each other. 11. The battery management method according to claim 10, wherein the difference between the updated correction value and the initial value is proportional to the first difference or is proportional to the first difference and the first difference. The difference between the two differences is proportional. 12. The battery management method according to claim 10, further comprising: determining the first candidate value as the SOC when the first difference is greater than a threshold; and When the first difference value is equal to or smaller than the threshold value, the second candidate value is determined as the SOC. 13. The battery management method according to claim 10, further comprising updating the correction value using the following equation:

Wherein, D ₁ represents the first difference, D ₂ represents the second difference, M ₁ represents the first weight, M ₂ represents the second weight, and E _correct represents the updated correction value. 14. The battery management method according to claim 10, further comprising, when the second difference is equal to or greater than the first difference, updating the correction value to be equal to the initial value. 15. The battery management method according to claim 10, further comprising: selectively outputting a switching signal for controlling a switch mounted on a current path of the battery, and When the second difference is smaller than the first difference, the duty cycle of the switching signal is adjusted to be lower than a reference duty cycle.

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